Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 041011
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
411 AM MDT TUE AUG 4 2015

.SYNOPSIS...HIGH PRESSURE WILL BRIEFLY BUILD ACROSS THE
REGION TODAY...BEFORE A WEAK COLD FRONT CROSSES NORTHERN UTAH
WEDNESDAY. MONSOONAL MOISTURE WILL RETURN TO THE REGION LATE IN
THE WEEK.

&&

.SHORT TERM (THROUGH 06Z FRIDAY)...THE UPPER LOW WHICH BROUGHT
WIDESPREAD RAINFALL TO MUCH OF NORTHERN UT DURING THE DAY MONDAY
CONTINUES TO DRIFT NORTHEASTWARD ACROSS CENTRAL WY...AND AWAY FROM
THE FORECAST AREA. IN ITS WAKE MID LEVEL RIDGING WILL BRIEFLY
AMPLIFY ACROSS THE EASTERN GREAT BASIN TODAY. LARGE SCALE
SUBSIDENCE ASSOCIATED WITH THIS BUILDING RIDGE SHOULD
SIGNIFICANTLY LIMIT ANY CONVECTIVE DEVELOPMENT THIS AFTERNOON
DESPITE LINGERING BOUNDARY LAYER MOISTURE. LOWERED MAX
TEMPERATURES A BIT ACROSS NORTHERN UT...WHERE A STABLE BOUNDARY
LAYER AIR MASS IN THE WAKE OF MONDAYS PRECIPITATION WILL LIKELY
BE STUBBORN...AND SLOW TO FULLY MIX OUT.

A SHORTWAVE TROUGH EMBEDDED WITHIN A DEEP LAYER SOUTHWESTERLY
FLOW IS FORECAST TO EJECT INLAND AND ACROSS THE NORTHERN GREAT
BASIN DURING THE DAY WEDNESDAY. ANY THREAT OF PRECIP WITH THIS
WAVE WILL REMAIN CONFINED TO THE ID BORDER REGION...AS WELL AS
PERHAPS THE HIGH UINTAS AND WASATCH PLATEAU. STRENGTHENING
SOUTHWESTERLY FLOW AHEAD OF THIS WAVE WILL RESULT IN LOCALLY
BREEZY CONDITIONS ACROSS CENTRAL AND SOUTHERN UTAH.

IN THE WAKE OF THIS WAVE MID LEVEL RIDGING IS ONCE AGAIN FORECAST
TO BRIEFLY AMPLIFY ACROSS THE REGION THURSDAY. LINGERING MID LEVEL
MOISTURE IN THE WAKE OF THE WEDNESDAY WAVE WILL RESULT IN A SLIGHT
CHANCE OF CONVECTION ACROSS THE HIGHER TERRAIN...OTHERWISE
TEMPERATURES WILL REMAIN SEASONAL ACROSS THE FORECAST AREA.

.LONG TERM (AFTER 06 FRIDAY)...THE GLOBAL MODEL SOLUTIONS ARE
NEARLY IDENTICAL THROUGH THIS EXTENDED PERIOD WITH ONLY MINOR
SUBTLE DIFFERENCES. THEREFORE MODERATE CONFIDENCE IN THE SCENARIO.
BOTH THE EC AND GFS SHOW A TROUGH MOVING INTO CENTRAL CALIFORNIA
FRIDAY MORNING WHICH TAPS MOISTURE OVER BAJA CALIFORNIA AND SWEEPS
IT NORTHWARD INTO UTAH. THE GFS SHOWS PWS INCREASING RAPIDLY
FRIDAY ACROSS THE ENTIRE CWA WITH VALUES OF 0.75 TO 1 INCH BY
FRIDAY EVENING. THE NOSE OF THE JET ROUNDING THE BOTTOM OF THE
TROUGH WILL BE EDGING INTO WEST CENTRAL UTAH BY 00Z FRIDAY AS WELL
WHICH WILL CREATE ADDITIONAL LIFT FRIDAY AFTERNOON AND THROUGH THE
NIGHT ACROSS WESTERN AND NORTHERN UTAH. HAVE INCREASED POPS FRIDAY
AFTERNOON AND EXPANDED THEM NORTHWARD OVER WEST CENTRAL PORTIONS.
ALSO INCREASED POPS SOME FOR NORTHERN UTAH FRIDAY NIGHT AS THE JET
DYNAMICS AND 500 MB COLD ADVECTION COMBINE FOR EXTRA INSTABILITY.
PROBABLY HAVE NOT INCREASED POPS ENOUGH BUT WANTED TO SET THE
TREND.

AS THIS TROUGH MOVES NORTHEAST ACROSS THE CWA SATURDAY...PRIMARILY
NORTHERN UTAH AND SOUTHWEST WYOMING...THE ASSOCIATED COLD FRONT
WILL GENERATE MORE SHOWERS AND THUNDERSTORMS ACROSS THIS AREA.
WITH A 50 KT JET AND COLD POCKET ALOFT THERE IS A THREAT THAT SOME
OF THE THUNDERSTORMS COULD BECOME SEVERE...ESPECIALLY OVER BOX
ELDER COUNTY. DRY AIR WILL PUSH INTO THE SOUTHWEST PORTIONS OF THE
CWA SATURDAY MORNING AND SPREAD ACROSS MOST OF CENTRAL AND
SOUTHERN PORTIONS BY SATURDAY AFTERNOON. THE COMBINATION OF THE
SHOWERS AND THUNDERSTORMS AS WELL AS COLD FRONT MOVING IN ACROSS
NORTHERN UTAH EARLY SATURDAY AFTERNOON WILL LIKELY PREVENT TEMPS
FROM WARMING TOO MUCH...SO HAVE LOWERED MAX TEMPS ACROSS THE
NORTH.

IN THE WAKE OF THE COLD FRONT...CLEARING SKIES SATURDAY NIGHT WILL
ALLOW THE TEMPERATURES TO COOL RAPIDLY. HAVE LOWER TEMPS ACROSS
MUCH OF THE CWA BOTH SATURDAY NIGHT AND SUNDAY DUE TO THIS COOLER
AND STABLE AIR MASS.

TEMPERATURES REBOUND MONDAY AND TUESDAY AS A SOUTHWEST FLOW
DEVELOPS. MOISTURE IS SHOWN TO INCREASE TUESDAY OVER SOUTHERN AND
EASTERN PORTIONS OF THE CWA...WITH THE EC FASTER THAN THE GFS.
HAVE ADDED SOME MINOR POPS OVER THE HIGHER TERRAIN FOR TUESDAY
AFTERNOON.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL AT KSLC THROUGH THE TAF
PERIOD...WITH SOUTH WINDS TRANSITIONING TO THE NORTHWEST BETWEEN
19Z AND 20Z.

&&

.FIRE WEATHER...HIGH PRESSURE ALOFT WILL STRENGTHEN ACROSS THE
REGION TODAY...ALLOWING THE AIR MASS TO DRY WITH ONLY A SMALL
THREAT OF SHOWERS AND THUNDERSTORMS ACROSS THE FAR NORTH. A COLD
FRONT WILL CROSS NORTHERN UTAH DURING THE DAY WEDNESDAY BRINGING
WITH IT ANOTHER SMALL CHANCE FOR SHOWERS AND THUNDERSTORMS OVER
THE NORTH. AHEAD OF THIS FRONT BREEZY CONDITIONS ARE EXPECTED TO
DEVELOP ACROSS PORTIONS OF CENTRAL AND SOUTHERN UTAH...WHILE
DAYTIME RH VALUES FALL BELOW 15 PERCENT ACROSS THE VALLEYS. HIGH
PRESSURE ALOFT WILL BRIEFLY RETURN THURSDAY...BEFORE MONSOONAL
MOISTURE RETURNS FRIDAY INTO SATURDAY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...NONE.
&&

$$

SEAMAN/STRUTHWOLF

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)



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